The previously mentioned power generation technologies have historically played a major role in the global energy sector. In contrast, the technologies presented in this section, although existing for decades, have experienced a dramatic upward trend over the past 20 years.
3.4.1 Gas-fired power plants
Natural gas has played a very important role as an energy carrier for over a century. In fact, before there was electric municipal street lighting, the next best option was gas and oil lamps. One of the many occupations lost to development is thus lamplighter. Gas is widely used globally today, in various different applications. Besides electricity production, gas is used for cooking, for a wide array of chemical processes and production of steel and cement. In the power sector, gas-fired capacities provided almost a quarter of the world’s electricity production in 2017 (BP, 2018).
Natural gas, as an energy carrier for electricity production, has been used almost as long as electricity production itself. Initially, gas was used as fuel to fire boilers as an alternative to coal (Breeze, 2016). Afterwards, the first industrial heavy-duty gas turbine was commissioned in the 1930s (Eckardt & Rufli, 2002). However, it was only until the 1990s, with the development of the combined-cycle gas turbine (CCGT), that the number of global installations of gas-fired power plants increased dramatically (Breeze, 2016).
Figure 13 shows the global development of the installation of gas-fired capacities.
Figure 13: Global installations of gas-fired capacities for the period 1940–2014.
Gas-fired capacities are part of the “Rising stars” because as seen in Figure 13 and as indicated by Breeze (2016), there has been a dramatic increase in global installations over the past three decades. Although the tendency seems to be stabilising around 50 GW to 60 GW per year, the level of yearly installations up to 2014 is still quite significant.
From a geographical distribution standpoint, the country hosting the highest share of the gas capacities is the United States with 31.2% of the global active installed capacities by 2014. The United States is followed by Russia and Japan, together hosting 42.9% of the global capacities. However, compared with the previously presented technologies, gas-fired capacities are the most widely distributed technology geographically, as the top 10 countries host 61.3% of the global gas-fired capacities.
The widespread usage of gas-fired capacities is probably due to their several advantages.
They represent a well-established technology, significantly more efficient than other fossil-fuelled technologies, particularly when configured as combined cycle gas turbines.
Furthermore, gas-fired capacities are highly flexible in their operation and have significantly less emissions per unit of electricity than for example coal-fired capacities (IPCC, 2014). In addition, gas as a fuel is relatively easy to store and transport and thereby to trade. Last but not least, gas-fired capacities have the capacity to adapt to synthetic fuel sources of less or neutral carbon footprint, such as biomethane, syngas and biogas.
3.4.2 Solar photovoltaic power plants
Solar energy is the “mother” of energy sources. Solar energy feeds the crops that feed us, helps us absorb vitamins and gives us warmth. From the energy system’s perspective, solar energy is the most abundant and widespread of energy sources, and is directly or indirectly responsible for other energy sources, such as hydropower (water evaporated by the sun condensing in the sky), wind (differences in the atmospheric air temperature generating drafts) and biofuel (allowing plants to absorb carbon through photosynthesis and grow). Currently, the most common way to directly transform solar irradiation into electricity is the use of solar photovoltaics.
Solar photovoltaics (PV) as a concept is not particularly new. The device to measure direct normal irradiance was already in use in the 1920s (Yang et al., 2018), and already back then there was significant discussion among academics about the potential of solar PV (Verhees et al., 2013). Further attention to the field was given in the 1950s when the first solar cells were being developed for the space industry simultaneously in different places (Verhees et al., 2013; Zhang and He, 2013).
Furthermore, the oil crisis in the 1970s reignited the conversation on the need to reduce the dependence on fossil fuels and further look into renewables, such as solar PV (Verhees et al., 2013). Consequently, governments started pushing for investment programs into the development of production of solar cells. Today’s largest solar cell producing country, China, started industrialising the production of solar cells in the mid-1980s (Zhang and He, 2013), opening two production lines. Thereafter, since 1993, the production of solar cells in China has experienced a dramatic increase between 20% and 30% annually (Zhang and He, 2013).
Solar PV is one of the rising stars for two main reasons. First, utility-scale installations are relatively recent compared with other well-established technologies. Second,
installations of solar PV capacities have experienced a significant increase over the last two decades. Figure 14 shows the global cumulative solar PV installations between 2000 and 2014, reaching around 180 GW. Between 2014 and 2019, the cumulative capacity of PV has more than tripled to around 580 GW of installed capacities (EC, 2018; IRENA 2020), with over 100 GW installed in 2018 only (PV-Tech, 2019). However, the 2014 point is used as a reference as it is the last year used for the analysis for the other technologies, with single power plant data used for Publications I, II and VII.
Unlike previously mentioned technologies, solar PV has not yet peaked in installations, and the exponential growth of installations globally is undeniable and continuous, as shown in Figure 14. This constant and dramatic increase in installations often surpasses the “optimistic” forecasts of models from research groups and even well-established institutions (Creutzig et al., 2017).
Figure 14: Global cumulative installations of solar PV capacities for the years 2000 to 2014.
This dramatic constant increase in yearly installations is the result of many factors; for one, the zero emissions operation of solar PV electricity production in a society of increasing awareness of climate change, but there are also many others. For example, solar PV is correlated with the highest job generation among electricity generation technologies (Cartelle Barros et al., 2017; Ram et al., 2019), the modularity and scalability of the technology, but probably most importantly, the dramatic drop in the capital cost of PV modules as well as the cost of balancing systems and installation (Comello et al., 2018; Crago and Koegler 2018).
Despite solar irradiation being widely available globally to a certain capacity, as some sites are obviously better than others, at least by 2014, the majority of solar PV installed capacities are still concentrated in a few countries. Germany is the country with the highest share of installed capacities in 2014, with 21.4% of the global solar PV installed
capacity. Together with the next two countries, China and Japan, the top 3 countries with solar PV installations in 2014 hosted 50.7% of the global capacity. The top 10 countries with solar PV installations hosted 84.4% of the global capacity in 2014.
3.4.3 Wind power
Much like hydropower, the mechanical power of wind has been harvested by humans for centuries. Wind power propelled the sail boats that allowed intercontinental exploration since the times before ancient Egyptians, and in more recent centuries it powered grain mills and water pumps. Moreover, the harvesting of wind for electricity generation is also not a particularly new concept. Electricity generation by wind turbines can be first traced back to the late 1880s in the UK and the USA, and horizontal axis wind turbines (like the ones most commonly used today) started development and operation in Denmark in the 1890s (IRENA 2018).
However, modern wind farms have been put into operation in relatively more recent times, since the 1970s. Therefore, wind power is one of the world’s rising stars, not only because of its rather recent resurgence, but because of the magnitude of that resurgence.
The rapid increase in wind turbine commissioning can be explained by the constant evolution of the technology, as in the mid-1980s the standard wind turbine had some 50 kW of capacity and rotor diameters of around 15 m. In contrast, nowadays, standard wind turbines have capacities of 3–5 MW and rotor diameters of around 164 m. Together with the impressive capacity evolution, there has also been a significant reduction in investment cost per unit of capacity, dropping by around 27% only between 2010 and 2016, and with further cost reductions expected (Partridge, 2018).
A good example of the potential of wind power has recently been given by Denmark. In the past few years, Denmark has occasionally covered its electricity demand entirely with the output of its windfarms, and at least in one occasion up to 140% of the demand (The Guardian, 2015; The Independent, 2017). In Denmark, during 2016, wind power accounted for 45% of the country’s electricity generation (The Independent, 2017).
Figure 15 shows the global cumulative installations of wind capacities between 1985 and 2014. As seen in Figure 15, the growth in global installed capacities has soared by a factor of over 175 in only two decades between 1994 and 2014, from around 2 GW of installed capacity in 1994 to over 370 GW in 2014. Furthermore, only between 2014 and 2019, an additional 273 GW (a 78.3% growth) has been commissioned globally (IRENA, 2020).
From a geographic distribution perspective, the champion of wind power commissioning is China, with 30.9% of the global installations by 2014. Similar to the case of solar PV, despite the wide availability of the resource globally, the top 3 countries alone host 58.7%
of the global installed wind capacity. Close to the values of solar PV, the top 10 countries also hosted 83.9% of the wind global installed capacities globally by 2014.
Figure 15: Global cumulative installations of wind capacities for the years 1985 to 2014.